1.
Learning the steps of literature
search process
2.
Understanding MeSH
3.
Determining the database
searching techniques
4.
Conducting an advance search in
PubMed
5.
Accessing the literature
Essential terminologies for literature
searches
ü
Keyword: These are the words or phrases that
researcher types in search engine/database. Keywords defines the questions/concepts
we are searching about, and results are displayed accordingly. Narrower (specific)
the keyword is, higher the chance of getting appropriate results.
üMeSH (Medical subjects headings) is the national library
of medicine-controlled vocabulary thesaurus, used for indexing articles for the
MEDLINE/PubMed databases. Each article citation is associated with a set of
MeSH terms that describes contents of citation. MeSH terms are organized in a
tree with sixteen main branches such as anatomy, organisms, disease,
publication characteristics and so on. Searching with MeSH is preferred over
keyword searching.
Stepwise methods of searching literature
1.
Break down the search topic into different steps:
ü Depending on types of data we are searching, keywords are
also constructed accordingly.
ü Generally our search topics for experimental study results
contain intervention, diagnosis and outcome keywords.
Eg: chemotherapeutic agents for breast carcinoma. Here four major keywords are used (chemotherapy, agents,
breast and carcinoma)
2.
Gathering keywords
üFor gathering keywords, Google, Google scholar and
Wikipedia are used
ü Google search shows thousands of results for any keywords,
including journals, official and personal websites, blogs and patient
information sites. most of information by random searching are of no use.
Results can be limited by directing googles algorithms to particular types of
sources like site.gov, site.edu, site.org at the end of keyword. Generally limiting .gov is preferred one to
get more relevant results (governmental agencies provides data on .gov. country
shortcut)
Here, keyword 'peptic ulcer' is typed by applying two methods- random searching and specifying the algorithms. Former search showed large number of sites designed to provide general information and later displayed only governmental sites with authentic results.
ü Wikipedia is preferred to get background information, and
references & external websites. But, content itself is not preferred in
scientific communities.
ü Google scholar provides scholarly information like books,
Journals articles and patents. One special characteristic of google scholars is
it shows results in order that higher the article is sited for, higher will be
the rank-older articles are prone to be ranked high.
3.
Search the concepts separately in PubMed
ü Once we done with gathering keywords, we now search that
particular keyword in PubMed search box.
ü Relevant MeSH terms (medical subjects headings) are
searched. It’s the set of controlled vocabulary terms used by national library
of medicines. In pubmed, articles are assigned in subject specialists who read
over the article and determines the subjects contents. Applying MeSH term
ensures that articles in same subjects are grouped together regardless of the
vocabulary used by author. MeSH descriptors are arranged in a tree structure
that allows to search the different level of specificity
Here, firstly the search icon was changed to MeSH, then keyword is typed, total of 15 major MeSH were displayed, Each heading again contains subheadings arranged in a typical tree format.
4. Apply additional Database search techniques
I. Truncation
ü Addition of symbol using an asterisk at the end of word
stem to find variant of root word and this is very useful to find synonyms. Eg:
incubat* (incubator, incubation, incubating, incubated, incubates)
II Quotation Marks keep terms together and in order. Eg: cervical cancer metastasis contains three keywords which can be represented as one by
“cervical cancer metastasis”.
III.Parentheses: allows users to
combine the concepts. They are used in the same manner that are being used in
mathematics equation and allows ordering the set of terms. Eg oesophageal
carcinoma (adenocarcinoma).
IV. Boolean operators
ü They are used to narrow the search and helps to find the
relationship between the search terms when searching in electronic databases.
ü Three Boolean operators are AND, OR and NOT.
ü AND narrows the search by combining together two separate
topics. Putting treatment And outcome Helps to find the article
which contains both these concepts. Eg: child* AND “head injury”. Quotation
marks is used to keep two words as a phrase and * to find the variants on this
word.
ü Using OR Boolean operators broaden the search and this is
often used with synonyms child* OR paediatrics OR infants* OR adolescence*.
ü Using NOT will narrow the search. It helps to remove the
terms we want to exclude. Eg: childhood diarrhoea NOT rotavirus.
here, I searched for Tamsulosin and 'benign prostatic hyperplasia', by applying AND & OR. former showed 838 results where both the terms are being used, and later showed 14359 results where either of these two terms are used.
use of NOT is dependent on knowledge & understanding of researcher.
5. Apply filter:
Filtering article according to our wish is available in pubmed, on the left hand side of the result. Applying filter reduces the number of articles significantly and increases the accuracy.
also, literatures can be filtered by author name. After entering keyword/MeSH, authors short name in this bracket […] will show exact literature you are searching for..
Thank You !!!
References:
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